A lawyer said he hoped a review could be heard as soon as this Friday.

A Save Me spokesman said the decision to grant an extension in Gloucestershire went against the advice of Natural England's own scientific advisor.

They claimed an urgent review was needed because the extension was already in operation and the period of the extension might elapse before a formal review could be applied.

The eight-week extension to the cull is due to end on 18 December.

John Cooper QC, who is representing the group, said: "From the material I have seen already, it is clear that appropriate procedures have not been taken in relation to this action, which will inevitably lead to the destruction of more wildlife if the government remains unchallenged.

"In all the circumstances and for the grounds we have set out, we assert that the decisions made by Defra, the Secretary of State and Natural England, separately and or cumulatively were unreasonable and should be immediately revoked."